Light Emitting Diode and Fabrication Method Thereof

ABSTRACT

A light-emitting diode includes a light-emitting epitaxial laminated layer with an upper surface; an ohmic contact layer over the light-emitting epitaxial laminated layer; an expanding electrode over the ohmic contact layer; a transparent insulating layer that covers the expanding electrode and the exposed ohmic contact layer, having a hole through the transparent insulating layer in a position corresponding to the expanding electrode; and a welding wire electrode over the transparent insulating layer and coupled to the expanding electrode via the hole.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of, and claimspriority to, U.S. patent application Ser. No. 15/871,289 filed on Jan.15, 2018, which is a continuation of, and claims priority to,PCT/CN2017/085660 filed on May 24, 2017, which claims priority toChinese Patent Application No. 201610413139.8 filed on Jun. 13, 2016.The disclosures of these applications are hereby incorporated byreference in their entirety.

BACKGROUND

In recent years, light-emitting diode (LED) is widely applied and playsan increasingly important role in various fields like display system,lighting system and automobile tail light.

SUMMARY

The inventors of the present disclosure have recognized that, in theexisting big-power light-emitting diode, light is emitted from the lowerpart of the welding wire electrode. Therefore, the existing big-powerlight-emitting diode suffers low light extracting rate due to lightabsorption by electrodes.

FIG. 1 shows an existing big-power light-emitting diode structure wherelight is emitted from the P-side, wherein, a light-emitting epitaxiallaminated layer 150 is bonded to the conductive substrate 100 via ametal bonding layer 110; an ohmic contact layer 160 is fabricated overthe upper surface of the light-emitting laminated layer 150, and a firstwelding wire electrode 171 and a second welding wire electrode 172 areformed over the ohmic contact layer 160. Though meeting big power needs,this structure itself is of great waste. Referring to FIG. 2, the secondwelding wire electrode (wiring electrode) in the design is large. Whencurrent is connected, a high proportion of current is input to theactive layer under the first welding wire electrode for recombinationluminescence. A large majority of emitted light is absorbed or blockedby the first welding wire electrode, and cannot be emitted from theepitaxial surface, causing great waste of current. In addition, lightemitted from the light-emitting region to the lower part of the secondwelding wire electrode is also absorbed and blocked, which greatlyinfluences light extraction rate of LED.

To solve the above problems, the present disclosure provides alight-emitting diode and fabrication thereof, where, no light is emittedfrom the lower part of the welding wire electrode. This structure isdesigned with a patterned ohmic contact layer. With a combination of atransparent insulating layer, an expanding electrode and a welding wireelectrode, the lower part of the welding wire electrode has no ohmiccontact and is far from the ohmic contact layer as much as possible.

The technical scheme of the present disclosure to solve the aboveproblems is: a light-emitting diode, which includes: a light-emittingepitaxial laminated layer, including a first semiconductor layer, anactive layer and a second semiconductor layer, wherein, the uppersurface is divided into an ohmic contact region and a non-ohmic contactregion; an ohmic contact layer in the ohmic contact region of thelight-emitting epitaxial laminated layer; an expanding electrode overthe ohmic contact layer, at least a part of which extends towards theedge of the ohmic contact layer to the non-ohmic contact region of thelight-emitting epitaxial laminated layer, and contacts with the uppersurface of the light-emitting epitaxial laminated layer; a transparentinsulating layer that covers the expanding electrode, the exposed ohmiccontact layer and the upper surface of the light-emitting epitaxiallaminated layer; a current channel that is in and runs through thetransparent insulating layer, and connects to the expanding electrode,wherein, the projection on the light-emitting epitaxial laminated layeris in the non-ohmic contact region; a welding wire electrode over thetransparent insulating layer, which connects to the expanding electrodevia a current channel, wherein, the projection on the light-emittingepitaxial laminated layer is in the non-ohmic contact region; whencurrent is input, current quickly flows to the ohmic contact region ofthe light-emitting epitaxial laminated layer along the current channelunder the welding wire electrode, so that no current is input to theactive layer under the welding wire electrode for lighting.

In some embodiments, the lower part of the welding wire electrode andnearby regions have no ohmic contact layer.

In some embodiments, the non-ohmic contact region over the upper surfaceof the light-emitting epitaxial laminated layer is larger than thewelding wire electrode.

In some embodiments, the current channel is distal from the ohmiccontact layer as much as possible.

In some embodiments, the non-ohmic contact region is distributed at bothends of the upper surface of the light-emitting epitaxial laminatedlayer, and the expanding electrode is a series of parallel linearstructure, in which, the first and last ends are in the non-ohmiccontact region, and the mid part contacts with the ohmic contact layer.

In some embodiments, refractive index of the transparent insulatinglayer is between that of the light-emitting epitaxial laminated layerand air.

In some embodiments, the transparent insulating layer, thelight-emitting epitaxial laminated layer, and the welding wire electrodeform an omnidirectional reflection system to avoid light absorption bythe welding wire electrode.

In some embodiments, the lower surface of the light-emitting epitaxiallaminated layer is provided with a reflector.

The present disclosure also provides a fabrication method of thelight-emitting diode, including: 1) forming a light-emitting epitaxiallaminated layer and an ohmic contact layer, wherein, the light-emittingepitaxial laminated layer includes a first semiconductor layer, anactive layer and a second semiconductor layer; 2) defining an ohmiccontact region and a non-ohmic contact region over the ohmic contactlayer surface, and removing the ohmic contact layer in the non-ohmiccontact region to expose the light-emitting epitaxial laminated layer;3) forming an expanding electrode over the ohmic contact layer, a leasta part of which extends towards the edge of the ohmic contact layer tothe non-ohmic contact region of the upper surface of the light-emittingepitaxial laminated layer, and directly contacts with the exposedlight-emitting epitaxial laminated layer; 4) forming a transparentinsulating layer that covers the expanding electrode, the exposed ohmiccontact layer and the upper surface of the light-emitting epitaxiallaminated layer; 5) forming a current channel over the formedtransparent insulating layer, which connects to the expanding electrode,wherein, the projection on the light-emitting epitaxial laminated layeris in the non-ohmic contact region; and 6) forming a welding wireelectrode over the transparent insulating layer, which connects to theexpanding electrode via the current channel, wherein, the projection onthe light-emitting epitaxial laminated layer is in the non-ohmic contactregion; when current is input, current quickly flows to the ohmiccontact region of the light-emitting epitaxial laminated layer along thecurrent channel at the lower portion of the welding wire electrode, sothat no current is input to the active layer under the welding wireelectrode for lighting.

The present disclosure also provides another fabrication method oflight-emitting diode, including: 1) forming a light-emitting epitaxiallaminated layer over the growth substrate, including a firstsemiconductor layer, an active layer and a second semiconductor layerhaving a first surface and a second surface opposite to each other,wherein, the first surface is far from the growth substrate, and isdivided in to an ohmic contact region and a non-ohmic contact region; 2)forming an ohmic contact layer in the ohmic contact region of the firstsurface of the light-emitting epitaxial laminated layer; 3) fabricatingan expanding electrode over the ohmic contact layer, a least a part ofwhich extends towards the edge of the ohmic contact layer to thenon-ohmic contact region of the light-emitting epitaxial laminatedlayer, and contacts with the light-emitting epitaxial laminated layer;4) providing a temporary substrate, and binding it to the first surfaceof the light-emitting epitaxial laminated layer; 5) removing the growthsubstrate to expose the second surface of the light-emitting epitaxiallaminated layer; 6) forming a reflector over the second surface ofexposed light-emitting epitaxial laminated layer; 7) providing aconductive substrate, and binding it to the reflector; 8) removing thetemporary substrate to expose the expanding electrode, a part of thelight-emitting epitaxial laminated layer surface and the ohmic contactlayer; 9) forming a transparent insulating layer, which covers theexpanding electrode, the exposed ohmic contact layer and the firstsurface of the light-emitting epitaxial laminated layer; 10) setting acurrent channel over the formed transparent insulating layer, whichconnects to the expanding electrode, wherein, the projection on thelight-emitting epitaxial laminated layer is in the non-ohmic contactregion; and 11) forming a welding wire electrode over the transparentinsulating layer, which connects to the expanding electrode via thecurrent channel, wherein, the projection on the light-emitting epitaxiallaminated layer is in the non-ohmic contact region.

In another aspect, a light-emitting system is provided including aplurality of light-emitting diodes described above. The light-emittingsystem can be used in the applications of lighting, display, signage,etc.

The other features and advantages of various embodiments of the presentdisclosure will be described in detail in the following specification,and it is believed that such features and advantages will become moreobvious in the specification or through implementations of thisdisclosure. The purposes and other advantages of the present disclosurecan be realized and obtained in the structures specifically described inthe specifications, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and constitute a part of thisspecification, together with the embodiments, are therefore to beconsidered in all respects as illustrative and not restrictive. Inaddition, the drawings are merely illustrative, which are not drawn toscale.

FIG. 1 illustrates a side sectional view of an existing big-powerlight-emitting diode where light is emitted from the P-side.

FIG. 2 shows a current flow diagram of the light-emitting diode as shownin FIG. 1.

FIG. 3 illustrates a side sectional view of a big-power light-emittingdiode where light is emitted from the P-side according to someembodiments of the present disclosure.

FIG. 4 illustrates a sectional view for the electrode fabricationprocess of the light-emitting diode chip according to some embodimentsof the present disclosure.

FIG. 5 shows a current flow diagram of the light-emitting diode as shownin FIG. 3.

FIG. 6 illustrates a side sectional view of a light-emitting diodeaccording to some embodiments of the present disclosure.

FIG. 7 illustrates an electrode fabrication process of thelight-emitting diode chip according to some embodiments of the presentdisclosure.

In the drawing: 100, 200: conductive substrate; 110, 210: metal bondinglayer; 120, 220: conductive reflective layer; 130, 230: medium layer;140, 240: N-type ohmic contact layer; 150, 250: light-emitting epitaxiallaminated layer; 151, 251: N-type current spreading layer; 152, 252:N-type cladding layer; 153, 253: active layer; 154, 254: P-type claddinglayer; 155, 255: P-type window layer; 160, 260: P-type ohmic contactlayer; 170, 270: top electrode; 171: first welding wire electrode; 172:second welding wire electrode; 250 a: ohmic contact region; 250 b:non-ohmic contact layer; 271: expanding electrode; 272: welding wireelectrode; 273: current channel; 280: transparent insulating layer.

DETAILED DESCRIPTION

Various embodiments of the present disclosure will be described indetail with reference to the accompanying drawings and examples, to helpunderstand and practice the disclosed embodiments, regarding how tosolve technical problems using technical approaches for achieving thetechnical effects. It should be understood that the embodiments andtheir characteristics described in this disclosure may be combined witheach other and such technical proposals are deemed to be within thescope of this disclosure without departing from the spirit of thisdisclosure.

With reference to FIG. 3, a light-emitting diode of the presentdisclosure includes: a conductive substrate 200, a metal bonding layer210, a conductive reflective layer 220, a transparent dielectric layer230, a light-emitting epitaxial laminated layer 250, an ohmic contactlayer 260, an expanding electrode 271, a transparent insulating layer280 and a welding wire electrode 272, wherein, the conductive substrate200 can be Si substrate; the transparent dielectric layer 230 isprovided with a series of N-type contact layer points 231; thetransparent dielectric layer 230 and the conductive reflective layer 220form an omnidirectional mirror system; the upper surface of thelight-emitting epitaxial laminated layer 250 is divided into an ohmiccontact region 250 a and a non-ohmic contact region 250 b; an ohmiccontact layer 260 is formed in the ohmic contact region 250 a of thelight-emitting epitaxial laminated layer 250, and the expandingelectrode 271 is formed over the ohmic contact layer 260, a part ofwhich extends towards the edge of the ohmic contact layer to thenon-ohmic contact region 250 b of the light-emitting epitaxial laminatedlayer, and contacts with the upper surface 250 b of the light-emittingepitaxial laminated layer; the transparent insulating layer 280 coversthe expanding electrode 271, the exposed ohmic contact layer 260 and theupper surface 250 b of the light-emitting epitaxial laminated layer; thecurrent channel 273 is in and runs through the transparent insulatinglayer 280, and connects to the expanding electrode 271, wherein, theprojection on the light-emitting epitaxial laminated layer is in thenon-ohmic contact region 250 b; the welding wire electrode 272 is overthe transparent insulating layer 280, which connects to the expandingelectrode 271 via the current channel 273, the projection of which onthe light-emitting epitaxial laminated layer is in the non-ohmic contactregion 250 b.

Details will be given below for the above light-emitting diode incombination with the fabrication method. The fabrication method mainlyincludes growth of the epitaxial laminated layer, patterning of theohmic contact layer, fabrication of the expanding electrode, twicesubstrate transfer and fabrication of the insulating layer and thewelding wire electrode.

I. Fabricate the Epitaxial Laminated Layer.

Form a light-emitting epitaxial laminated layer 250 over the growthsubstrate. The substrate can be sapphire, AlN, GaN, Si, SiC, GaAs andother materials, and the surface structure can be a plane structure or apatterned structure. When applied current flows through thelight-emitting epitaxial laminated layer, the active layer is triggeredto emit light. When the active layer is made of nitride-based material,blue or green light will be emitted; when made of AlInGaP-basedmaterial, red, orange or yellow light in amber color will be emitted. Inanother embodiment, the active layer is AlInGaP-based material.Therefore, the ohmic contact layer 260 is semiconductor material, whichis formed with the light-emitting epitaxial laminated layer viaepitaxial growth. Details are as follows: Form a stopping layer, anN-type ohmic contact layer 240, an N-type current spreading layer 251,an N-type cladding layer 252, an active layer 253, a P-type claddinglayer 254, a P-type window layer 255 and a P-type ohmic contact layer260 over the GaAs substrate in successive, wherein, the N-type currentspreading layer 251, the N-type cladding layer 252, the active layer253, the P-type cladding layer 254 and the P-type window layer 255 forma light-emitting epitaxial laminated layer 250.

II. Patterning the Ohmic Contact Layer and Fabricate the ExpandingElectrode.

Referring to FIG. 4, panel (a), define an ohmic contact region 250 a anda non-ohmic contact region 250 b over the surface of the light-emittingepitaxial laminated layer 250. In this embodiment, the chip appearsrectangle. The non-ohmic contact region 250 b is distributed at bothends of the upper surface of the light-emitting epitaxial laminatedlayer. Remove the ohmic contact layer of the non-ohmic contact region250 b to expose the P-type window layer 255 of the light-emittingepitaxial laminated layer.

Referring to FIG. 4, panel (b), fabricate an expanding electrode 271.This expanding electrode 271 is a series of parallel linear structure,in which, the first and last ends are in the non-ohmic contact region250 b, and the mid part contacts with the P-type ohmic contact layer260.

III. Transfer the Substrate.

First, transfer the substrate for the first time. Specifically, providea temporary substrate, and bind it to the P-side surface (In thisembodiment, the P-side surface includes surfaces of the P-type ohmiccontact layer 260, the expanding electrode 271 and the P-type windowlayer 255) of the light-emitting epitaxial laminated layer 250, andremove the growth substrate to expose the N-side surface of thelight-emitting epitaxial laminated layer. In this embodiment, expose theN-type ohmic contact layer 251; and fabricate a reflector over thesurface of the exposed light-emitting epitaxial laminated layer. In apreferred embodiment, etch a part of the N-type contact layer and remainsome ohmic contact points 231. Deposit a transparent medium layer 230and a conductive reflective layer 220 over the N-type ohmic contactlayer, wherein, the transparent medium layer 230 can be a single-layerstructure, or a distributed Bragg reflection layer structure withalternating-stacked materials with high and low refractive index; andthe conductive reflective layer 220 can be metal materials with highrefractive index, such as Ag and Al.

Next, transfer the substrate for the second time. Specifically, providea conductive substrate 200, and coat a metal bonding layer 210 over theconductive substrate 200 and the reflective layer 220 respectively forhigh temperature bonding so that the light-emitting epitaxial laminatedlayer is bonded to the conductive substrate 200; remove the temporarysubstrate to expose the P-side surface of the light-emitting epitaxiallaminated layer 250, thus finishing substrate transfer process.

IV. Fabricate the Transparent Insulating Layer and the Welding WireElectrode.

Cover a transparent insulating layer over the P-side surface of theexposed light-emitting epitaxial laminated layer 250. Referring to FIG.4, panel (c), deposit a transparent insulating layer 280, which coversentire upper surface of the sample, which comprises an expandingelectrode 271, an exposed P-type ohmic contact layer and a P-type windowlayer. This transparent insulating layer 280 users high-transparencymedium, wherein, n value is between that of air and the epitaxy, andthickness T=λ/4n, serving as an antireflection film in thelight-emitting region.

Referring to FIG. 4, panel (d), fabricate a current through hole 290over the transparent insulating layer, which corresponds to theexpanding electrode 271 of the non-ohmic contact region, and is distalfrom the P-type ohmic contact layer 260 as much as possible.

Referring to FIG. 4, panel (e), fabricate a welding wire electrode 272over the transparent insulating layer, the projection of which on thelight-emitting epitaxial laminated layer is in the non-ohmic contactregion 250 b, which fills the current through hole 290 to form a currentchannel so that a connection is built to the expanding electrode 271 toform a chip. The welding wire electrode 272 uses high-reflectivitymaterial, and prefers to be Ti/Pt/Au, Cr/Al/Ti/Pt/Au or Ti/Al/Pt/Austructure.

In the above light-emitting diode, the transparent insulating layer 280at least has the purposes in below: I. The transparent insulating layeris above the expanding electrode 271 and below the welding wireelectrode 272 to make current expands outwards. This reduces currentwaste of the active layer under the welding wire electrode and lightabsorption and blocking of the welding wire electrode; II. serve as anantireflection film of the light-emitting surface; III. form an ODRsystem together with the welding wire electrode and the P-type ohmiccontact layer 255, which reflects light emitted to the lower part of thewelding wire electrode; and IV. serve as a protection film to preventexternal or process scraps from adhering to the side wall of the chipcore, which may form an electric leakage path.

FIG. 5 illustrates a current flow diagram of the above light-emittingdiode. An insulating layer is provided below the welding wire electrode,which is far from the P-type ohmic contact layer, whose lower part andthe regions near the expanding electrode have no ohmic contact.Therefore, current directly flows to the active region along the currentchannel to achieve effective outward expansion of current. When externalpower is connected, as current takes priority to flow along the pathwith lowest resistance, it quickly flows to the ohmic contact region inthe active region along the current channel below the welding wireelectrode.

With reference to FIG. 6, a light-emitting diode according to someembodiments of the present disclosure includes: a conductive substrate200, a metal bonding layer 210, a conductive reflective layer 220, atransparent dielectric layer 230, a light-emitting epitaxial laminatedlayer 250, an ohmic contact layer 260, an expanding electrode 271, atransparent insulating layer 280 and a welding wire electrode 272,wherein, the conductive substrate 200 can be Si substrate; thetransparent dielectric layer 230 is provided with a series contactpoints 240; the transparent dielectric layer 230 and the conductivereflective layer 220 form an omnidirectional mirror system; the uppersurface of the light-emitting epitaxial laminated layer 250 is dividedinto an ohmic contact region 250 a and a non-ohmic contact region 250 b;the ohmic contact layer 260 is formed over the upper surface of thelight-emitting epitaxial laminated layer 250; and the expandingelectrode 271 is formed over the ohmic contact layer 260, which is in aposition corresponding to ohmic contact region 250 a and extends towardsthe non-ohmic contact region 250 b of the light-emitting epitaxiallaminated layer, in some embodiments, the expanding electrode 271 is aseries of parallel linear structure, in which, the first and last endsare in the non-ohmic contact region 250 b, and the mid part is in theohmic contact region 250 a; the transparent insulating layer 280 coversthe expanding electrode 271 and the exposed ohmic contact layer 260; acurrent channel 273 is in and runs through the transparent insulatinglayer 280, and connects to the expanding electrode 271, wherein, theprojection on the light-emitting epitaxial laminated layer is in thenon-ohmic contact region 250 b; the welding wire electrode 272 is overthe transparent insulating layer 280, which connects to the expandingelectrode 271 via the current channel 273, the projection of which onthe light-emitting epitaxial laminated layer is in the non-ohmic contactregion 250 b.

In the above light-emitting diode, first, the transparent insulatinglayer 280 is above the expanding electrode 271 and below the weldingwire electrode 272 to make current expands outwards, which reducescurrent waste of the active layer under the welding wire electrode andlight absorption and blocking of the welding wire electrode; second, thetransparent insulating layer 280 can serve as an antireflection film ofthe light-emitting surface, which improve the light extractionefficiency; third, the transparent insulating layer 280 form an ODRsystem together with the welding wire electrode and the ohmic contactlayer 260, which reflects light emitted to the lower part of the weldingwire electrode; and fourth, the transparent insulating layer 280 canserve as a protection film to prevent external or process scraps fromadhering to the side wall of the chip core, which may form an electricleakage path.

FIG. 7 illustrates a sectional view for the electrode fabricationprocess of the light-emitting diode as shown in FIG. 6.

First, referring to FIG. 7, panel (a), forming the ohmic contact layer260 over the upper surface of the light-emitting epitaxial laminatedlayer 250, in which, the material can be a semiconductor material or atransparent conductive material.

Next, referring to FIG. 7, panel (b), fabricate an expanding electrode271. In some embodiments, the chip appears rectangle, the upper surfaceof the light-emitting epitaxial laminated layer 250 is divided into anohmic contact region 250 a and a non-ohmic contact region 250 b, inwhich the non-ohmic contact region 250 b is distributed at both ends ofthe upper surface of the light-emitting epitaxial laminated layer andthe ohmic contact region 250 a is distributed in between the both ends,the expanding electrode 271 is a series of parallel linear structure, inwhich, the first and last ends are in the non-ohmic contact region 250b, and the mid parts are in the ohmic contact region 250 a.

Next, referring to FIG. 7, panel (c), deposit a transparent insulatinglayer 280, which covers entire upper surface of the sample, whichcomprises an expanding electrode 271, an exposed P-type ohmic contactlayer 260. This transparent insulating layer 280 users high-transparencymedium, wherein, n value is between that of air and the epitaxy, andthickness T=λ/4n, serving as an antireflection film in thelight-emitting region.

Next, referring to FIG. 7, panel (d), fabricate a current through hole290 over the transparent insulating layer, which corresponds to theexpanding electrode 271 of the non-ohmic contact region 250 b, and isdistal from the expanding electrode 271 as much as possible.

Referring to FIG. 7, panel (e), fabricate a welding wire electrode 272over the transparent insulating layer, the projection of which on thelight-emitting epitaxial laminated layer is in the non-ohmic contactregion 250 b, which fills the current through hole 290 to form a currentchannel so that a connection is built to the expanding electrode 271 toform a chip. The welding wire electrode 272 uses high-reflectivitymaterial, and prefers to be Ti/Pt/Au, Cr/Al/Ti/Pt/Au or Ti/Al/Pt/Austructure.

Although specific embodiments have been described above in detail, thedescription is merely for purposes of illustration. It should beappreciated, therefore, that many aspects described above are notintended as required or essential elements unless explicitly statedotherwise. Various modifications of, and equivalent acts correspondingto, the disclosed aspects of the exemplary embodiments, in addition tothose described above, can be made by a person of ordinary skill in theart, having the benefit of the present disclosure, without departingfrom the spirit and scope of the disclosure defined in the followingclaims, the scope of which is to be accorded the broadest interpretationso as to encompass such modifications and equivalent structures.

1. A light-emitting diode, comprising: a light-emitting epitaxiallaminated layer including: a first semiconductor layer; an active layer;and a second semiconductor layer; an ohmic contact layer over an uppersurface of the light-emitting epitaxial laminated layer; an expandingelectrode over the ohmic contact layer; a transparent insulating layerthat covers the expanding electrode and an exposed ohmic contact layerand having a hole through the transparent insulating layer in a positioncorresponding to the expanding electrode; and a welding wire electrodeover the transparent insulating layer and coupled to the expandingelectrode via the hole.
 2. The light-emitting diode of claim 1, wherein:an upper surface of the light-emitting epitaxial laminated layer isdivided into an ohmic contact region and a non-ohmic contact region′ theexpanding electrode is provided in the ohmic contact region and extendstowards to the non-ohmic contact region; and the welding wire electrodeis provided in non-ohmic contact region.
 3. The light-emitting diode ofclaim 2, wherein the non-ohmic contact region over the upper surface ofthe light-emitting epitaxial laminated layer is larger than the weldingwire electrode.
 4. The light-emitting diode of claim 2, wherein the holeis distal from the ohmic contact region as much as possible.
 5. Thelight-emitting diode of claim 2, wherein, the hole is provided in thenon-ohmic contact region.
 6. The light-emitting diode of claim 2,wherein, the non-ohmic contact region is distributed at both ends of theupper surface of the light-emitting epitaxial laminated layer; and theexpanding electrode is a series of parallel linear structure, in which,the first and last ends are in the non-ohmic contact region, and the midpart contacts with the ohmic contact layer.
 7. The light-emitting diodeof claim 1, wherein, refractive index of the transparent insulatinglayer is between that of the light-emitting epitaxial laminated layerand air.
 8. The light-emitting diode of claim 1, wherein, thetransparent insulating layer, the light-emitting epitaxial laminatedlayer, and the welding wire electrode form an omnidirectional reflectionsystem to avoid light absorption by the welding wire electrode.
 9. Thelight-emitting diode of claim 1, wherein, the transparent insulatinglayer in the ohmic contact region is λ/4n thick.
 10. The light-emittingdiode of claim 1, wherein, a lower surface of the light-emittingepitaxial laminated layer is provided with a reflector.
 11. Alight-emitting system including a plurality of light-emitting diodesaccording to claim
 1. 12. The light-emitting system of claim 11,wherein: an upper surface of the light-emitting epitaxial laminatedlayer is divided into an ohmic contact region and a non-ohmic contactregion; the expanding electrode is provided in the ohmic contact regionand extends towards to the non-ohmic contact region; and the weldingwire electrode is provided in non-ohmic contact region.
 13. Thelight-emitting system of claim 12, wherein the non-ohmic contact regionover the upper surface of the light-emitting epitaxial laminated layeris larger than the welding wire electrode.
 14. The light-emitting systemof claim 11, wherein the hole is provided in the non-ohmic contactregion.
 15. A fabrication method of a light-emitting diode, the methodcomprising: 1) forming a light-emitting epitaxial laminated layer,wherein, the light-emitting epitaxial laminated layer comprises a firstsemiconductor layer, an active layer and a second semiconductor layer;2) forming an ohmic contact layer over an upper surface of thelight-emitting epitaxial laminated layer; 3) forming an expandingelectrode over the ohmic contact layer; 4) forming a transparentinsulating layer over the expanding electrode which covers the expandingelectrode. the exposed ohmic contact layer, and having a hole throughthe transparent insulating layer in a position corresponding to theexpanding electrode; and 5) forming a welding wire electrode over thetransparent insulating layer, which connects to the expanding electrodevia the hole.
 16. A fabrication method of a light-emitting diode, themethod comprising: 1) forming a light-emitting epitaxial laminated layerover a growth substrate, comprising a first semiconductor layer, anactive layer and a second semiconductor layer having a first surface anda second surface opposite to each other, wherein, the first surface isdistal from the growth substrate; 2) forming an ohmic contact layer overthe first surface of the light-emitting epitaxial laminated layer; 3)fabricating an expanding electrode over the ohmic contact layer; 4)providing a temporary substrate, and binding it to the first surface ofthe light-emitting epitaxial laminated layer; 5) removing the growthsubstrate to expose the second surface of the light-emitting epitaxiallaminated layer; 6) forming a reflector over the second surface of thelight-emitting epitaxial laminated layer; 7) providing a conductivesubstrate, and binding it to the reflector; 8) removing the temporarysubstrate to expose the expanding electrode, a part surface of the ohmiccontact layer; 9) forming a transparent insulating layer, which coversthe expanding electrode and the exposed ohmic contact layer; 10) settinga hole though the transparent insulating layer in a positioncorresponding to the expanding electrode; and 11) forming a welding wireelectrode over the transparent insulating layer, which connects to theexpanding electrode via the hole. wherein the fabricated light-emittingdiode comprises: the light-emitting epitaxial laminated layer, whichcomprises: the first semiconductor layer; the active layer; and thesecond semiconductor layer; the ohmic contact layer over an uppersurface of the light-emitting epitaxial laminated layer; the expandingelectrode over the ohmic contact layer; the transparent insulating layerthat covers the expanding electrode and the exposed ohmic contact layerand having a hole through the transparent insulating layer in a positioncorresponding to the expanding electrode; and the welding wire electrodeover the transparent insulating layer, which connects to the expandingelectrode via the hole.
 17. The method of claim 16, wherein: the firstsurface of the light-emitting epitaxial laminated layer is divided intoan ohmic contact region and a non-ohmic contact region; the expandingelectrode is provided in the ohmic contact region and extends towards tothe non-ohmic contact region; and the welding wire electrode is providedin non-ohmic contact region.
 18. The method of claim 17, wherein thenon-ohmic contact region over the upper surface of the light-emittingepitaxial laminated layer is larger than the welding wire electrode. 19.The method of claim 17, wherein the hole is distal from the ohmiccontact region as much as possible.
 20. The method of claim 17, wherein:the non-ohmic contact region is distributed at both ends of the uppersurface of the light-emitting epitaxial laminated layer; and theexpanding electrode is a series of parallel linear structure, in which,the first and last ends are in the non-ohmic contact region, and the midpart contacts with the ohmic contact layer.